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SubjectRe: [PATCH 19/21] workqueue: introduce worker
Hi Tejun,

On 17/11/09 2:15 +0900, Tejun Heo wrote:
> Separate out worker thread related information to struct worker from
> struct cpu_workqueue_struct and implement helper functions to deal
> with the new struct worker. The only change which is visible outside
> is that now workqueue worker are all named "kworker/CPUID:WORKERID"
> where WORKERID is allocated from per-cpu ida.
>
> This is in preparation of concurrency managed workqueue where shared
> multiple workers would be available per cpu.
>
> Signed-off-by: Tejun Heo <tj@kernel.org>
> ---
> kernel/workqueue.c | 219 +++++++++++++++++++++++++++++++++++++---------------
> 1 files changed, 157 insertions(+), 62 deletions(-)
>
> diff --git a/kernel/workqueue.c b/kernel/workqueue.c
> index dce5ad5..6694b3e 100644
> --- a/kernel/workqueue.c
> +++ b/kernel/workqueue.c

[...]

> @@ -413,6 +426,105 @@ int queue_delayed_work_on(int cpu, struct workqueue_struct *wq,
> }
> EXPORT_SYMBOL_GPL(queue_delayed_work_on);
>
> +static struct worker *alloc_worker(void)
> +{
> + struct worker *worker;
> +
> + worker = kzalloc(sizeof(*worker), GFP_KERNEL);
> + return worker;
> +}
> +
> +/**
> + * create_worker - create a new workqueue worker
> + * @cwq: cwq the new worker will belong to
> + * @bind: whether to set affinity to @cpu or not
> + *
> + * Create a new worker which is bound to @cwq. The returned worker
> + * can be started by calling start_worker() or destroyed using
> + * destroy_worker().
> + *
> + * CONTEXT:
> + * Might sleep. Does GFP_KERNEL allocations.
> + *
> + * RETURNS:
> + * Pointer to the newly created worker.
> + */
> +static struct worker *create_worker(struct cpu_workqueue_struct *cwq, bool bind)
> +{
> + int id = -1;
> + struct worker *worker = NULL;
> +
> + spin_lock(&workqueue_lock);
> + while (ida_get_new(&per_cpu(worker_ida, cwq->cpu), &id)) {
> + spin_unlock_irq(&workqueue_lock);
> + if (!ida_pre_get(&per_cpu(worker_ida, cwq->cpu), GFP_KERNEL))
> + goto fail;
> + spin_lock(&workqueue_lock);
> + }
> + spin_unlock_irq(&workqueue_lock);
> +
> + worker = alloc_worker();
> + if (!worker)
> + goto fail;
> +
> + worker->cwq = cwq;
> + worker->id = id;
> +
> + worker->task = kthread_create(worker_thread, worker, "kworker/%u:%d",
> + cwq->cpu, id);
> + if (IS_ERR(worker->task))
> + goto fail;
> +
> + if (bind)
> + kthread_bind(worker->task, cwq->cpu);
> +
> + return worker;
> +fail:
> + if (id >= 0) {
> + spin_lock(&workqueue_lock);
> + ida_remove(&per_cpu(worker_ida, cwq->cpu), id);
> + spin_unlock_irq(&workqueue_lock);
> + }
> + kfree(worker);
> + return NULL;
> +}

AFAIU create_worker() should call spin_lock_irq() instead of spin_lock().

[...]

Thanks,

Louis

--
Dr Louis Rilling Kerlabs
Skype: louis.rilling Batiment Germanium
Phone: (+33|0) 6 80 89 08 23 80 avenue des Buttes de Coesmes
http://www.kerlabs.com/ 35700 Rennes[unhandled content-type:application/pgp-signature]
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